Polyphenylene ether resins are very useful thermoplastic resins because of their excellent heat resistance, mechanical characteristics, electrical characteristics, water resistance, acid resistance, alkali resistance and self-extinguishing properties.
It is expected that these resins will be used as engineering plastic materials in the fields of, for example, sealing materials for automobile ignition coils, cranks, gears and connectors for electrical components. However, these resins have a high glass transition temperature, and hence they have a high melt viscosity and poor moldability. Further, these resins have the disadvantage in that their impact resistance is poor in comparison with polyamides and polycarbonates.
To solve these problems, these resins have been blended with polyolefins or other engineering plastics such as polyamides, polycarbonates or polybutylene terephthalate. These two types of polymers have essentially poor compatibility, and molded articles prepared from these resins compositions are brittle and have low mechanical strength and low impact strength. Hence, the molded articles cannot be put to practical use. To solve these problems, compatibilizing agents have been used. See, in this regard, JP-B-1-17504 and JP-B-3-6185 (The term "JP-B" as used herein means an "examined Japanese patent publication"). Most of these compatibilizing agents are graft or block copolymers of both polyphenylene ether and the polymer to be blended. In the preparation of these copolymers, it is considered that the terminal phenolic hydroxyl group of the polyphenylene ether reacts with a functional group of the other polymer.
However, the species of functional groups which are capable of reacting with the above terminal phenolic hydroxyl group are limited. Hence, the range of the use thereof is also limited to certain applications. Accordingly, there have been proposed many functionalized polyphenylene ethers to improve the reactivity thereof. Many of such proposals involve an acid anhydride being introduced into the polyphenylene ether (see, JP-W-62-500456 (the term "JP-W" as used herein means an "unexamined published international patent application"), JP-A-63-10656 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and WO87/540) or an hydroxyl group being introduced into the polyphenylene ether (see, JP-A-63-128021 and JP-A-63-130660). The introduction of an amino group into the polyphenylene ether leads to problems because the amino group itself has high reactivity.
The following disclosure reflects a preparative example of an aminated polyphenylene ether as is given in Example 13 of JP-W-63-503391 (corresponding to WO87/7280 and U.S. Pat. No. 4,746,708).
A blend consisting of 100 parts (by weight) of polyphenylene ether and 0.5 parts of maleic anhydride was prepared in a Henschel mixer, and extruded through a twin-screw extruder at 330.degree. C. (extruder temperature). The resulting extrudate composed of an anhydride functionalized polyphenylene ether was quenched in a water bath and pelletized. There was thus obtained the final acid anhydride-functionalized polyphenylene ether.
To a solution of 10 g of the anhydride-functionalized polyphenylene ether in 100 ml of toluene there was added 3 ml of ethylenediamine while stirring in a nitrogen atmosphere. After stirring was continued for 6 hours, methanol was added thereto to precipitate an N-aminoalkylimide-functionalied polyphenylene ether. The product was re-precipitated from chloroform by using methanol and dried at 60.degree. C. under vacuum.
The above-described process required a multi-stage reaction comprising first preparing an unsaturated carboxylic acid-modified polyphenylene ether and then reacting it with ethylenediamine. In addition, the process has problems in that polyphenylene ether gels during the course of the reaction in the latter stage thereof or a high temperature melt reaction is necessary. No disclosure occurs concerning the yield of the aminated polyphenylene ether and the physical properties thereof in Example 13 of the aforesaid patent publication. In addition, no evaluation of the blend of the aminated polyphenylene ether with another resin was made.